The true northerner. [volume] (Paw Paw, Mich.) 1855-1920, 1887-07-06
MECHANICAL.

SILVER may be dissolved in nitric
acid, and again reduced to a metallic
state by adding copper, afte- removing
excess of moisture by evaporation.
Gold can be dissolved in warm nitro
muriatc acid. and it may be recovered
or reduced TO 3 metallic state by pre-
cipitating with copperas and then melt
ing the precipitate in crucible.
A MECHANICAL puzzle has been pro-
pounded like this: A pair of car
wheels and axle are resting on piece
OF level track, rope made fast to the
axle and so wound round it that when
the rope is pulled the tendency OF the
wheel is to come toward you, while at
the same time if the wheels must re-
volve they must move from you. Ii
the rope is pulled, III what direction
will the wheels run? Will they move
away from the spectator or toward
him? Further, ii the track is inclined,
say one in ten, the highest part of the
incline being nearest the spectator and
the end of the rope, and a considerable
strain being exerted on the rope, in
which direction will the wheels move,
up or down the incline?
ONE of the most adhesive and dura-
BILE of cements for uniting iron fur
naces is found to be the oxide of iron
itself. With this Joint can be made
so perfect and SOUND that the iron will
break before the cement will part. AS
an illustration of this statement the
fact is cited that in removing the cast
iron pipe OF bilge pump from ship
that had made four Atlantic voyages it
was found necessary to take the Sec
tons apart; the flanges had been past
ed with cement of cast-iron drillings
and filings mixed with sulphur and sal
ammoniac moistened with water; then
the nuts, three to each fange, were set
up on the bolts, and the union was
completed. The four voyages occu-
pied nearly year, and, on the separa-
ton CT the parts being attempted, even
the cold chisel failed to make a division
between the solid castings and the CO.
ments that interviewed. artisan.
FoR glue to be properly effective it
requires to penetrate the pores of the
wood, and the more a body of glue
penetrates the wood the more substan-
tial the joint will remain. Clues that
take the longest to dry are to be pre-
ferred to those that dry quickly, the
slow-drying CLUES being always the
strongest other things being equal.
For general use no method gives such
good results as the following: Break
the glue up small, put into an iron
kettle, cover the glue with water and
allow it to soak twelve hours; after
soaking boil until done. Then pour it
into an air-tight box; leave the cover
of until cold, then cover up tight. As
glue is required, cut out a portion and
melt in the usual way. Expose no more
of the made glue to the atmosphere
for any length of time than is neces-
sary, as the atmosphere is very de-
structive to made glue. Never heat
made glue in pot that is subjected to
the direct heat of the fire or lamp.
All such methods of heating glue can
not be condemned in terms too severe.
Do not use thick glue for joints or
veneering. In all cases work it well
into the wood in a similar manner to
what painters do with paint. Glue
both surfaces of your work, excepting
in case of veneering. Never glue upon
hot wood, or use hot cauls to veneer
with, as the hot wood will absorb all
the water in the glue too suddenly,
and leave only a very little residue,
with no adhesive power III it.-Ameri-
can HUeRtOr.